When you have your game library sorted alphabetically, some games aren't grouped together like they really should be. For example, you might want all the Yakuza games grouped together, but the newer games are called like a dragon and are completely separate. You could now go and have the like a dragon games sorted as if they were also named Yakuza, so that all the games are grouped together.

Another example for me personally is that I have a bunch of Metroid games on my deck, and almost all of them are grouped together, except for Super Metroid and AM2R. Now I can move those to be listed alongside the other Metroid games.

Things like Lightning Returns: Final Fantasy XIII can now be way up in the F’s with the rest of the FF games now.

Sounds like it will retain the actual name and display that to you, but you are giving it a name that is used to sort it alphabetically. Example could be you got a game that is named "The Game Title" it would probably put that into the T section instead of G so you give it the name "Game Title" for it to sort it, now it will be placed in the G section but still show the game title to you as "The Game Title"

RPS's example use case was making the Yakuza and Like A Dragon games show up in the right order. You could set the sort title of Yakuza Kiwami as, say, "Yakuza 1 Remake", to make it follow Yakuza 0, and make the Like A Dragon games sort like they're Yakuza games.

Looks like it's available in desktop mode too, so will work anywhere on Linux at the least.

I know you have your heart set on the remapping as the solution but I heavily encourage you to take advantage of the Steam Deck's extensive right-to-repair support and fix the buttons or swap the side PCBs out if that's what's broken and you can't solder. If its just the spring or the plastic, you can easily swap that.

At least CSS loader exists and works. Native theme support (probably through the point shop) would be nice though.